Initialize a new Cargo package

```shell
cargo init
```

By default cargo initializes a new package containing a *binary* crate.
The file that gets compiled into the binary is located at
`src/main.rs`. This is by convention and we can specify different paths
and names for binaries.

We also get a `Cargo.lock` and a `Cargo.toml`. These are similar to
JavaScript's `package.json` and `package-lock.json` or `yarn.lock`.
The `Cargo.toml` defines different features of our package including
`dependencies`, defining zero or one library crates, and defining as
many binary crates as we want.

We can run the new binary with `cargo run`.

```shell
❯ cargo run
   Compiling digital-garden-steps v0.1.0 (/digital-garden-steps)
    Finished dev [unoptimized + debuginfo] target(s) in 1.38s
     Running `target/debug/digital-garden-steps`
Hello, world!
```

.gitignore

@@ -1 +1 @@
-/target
+/target

Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "digital-garden-steps"
+version = "0.1.0"
+authors = ["Christopher Biscardi <chris@christopherbiscardi.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}